Meniscal rasping for repair of meniscal tear in the avascular zone.

We examined experimentally whether a longitudinal tear in the avascular zone of a rabbit meniscus can be healed by meniscal rasping. A full-thickness longitudinal tear 5-mm long was artificially created in the avascular zone of the anterior segment of both medial menisci. Meniscal rasping was then done on the femoral surface of the right meniscus from the parameniscal synovium to the inner segment including the tear. The left meniscus was left without further treatment as control. Two to 4 weeks after surgery, the hypertrophic synovium was observed invading from the parameniscal region to the injured portion. Eight to 16 weeks after surgery, the tear was almost completely healed. In contrast, neither hypertrophy of the synovium covering the tear nor healing was induced in the control meniscus. The mechanical test showed that there was a significant difference in the tensile strength and the stiffness of the injured portion between the rasped meniscus and the control meniscus. Meniscal rasping is easy to do, is effective, and causes few adverse effects with menisci. This procedure may be a treatment option for clinical cases of meniscal tear in the avascular zone for which we have no effective and clinically applicable methods at present, although further investigation is needed before clinical application.